1 //===--- NamespaceCommentCheck.cpp - clang-tidy ---------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "NamespaceCommentCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchers.h"
13 #include "clang/Lex/Lexer.h"
14 #include "llvm/ADT/StringExtras.h"
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace readability {
21 
22 NamespaceCommentCheck::NamespaceCommentCheck(StringRef Name,
23                                              ClangTidyContext *Context)
24     : ClangTidyCheck(Name, Context),
25       NamespaceCommentPattern("^/[/*] *(end (of )?)? *(anonymous|unnamed)? *"
26                               "namespace( +([a-zA-Z0-9_:]+))?\\.? *(\\*/)?$",
27                               llvm::Regex::IgnoreCase),
28       ShortNamespaceLines(Options.get("ShortNamespaceLines", 1u)),
29       SpacesBeforeComments(Options.get("SpacesBeforeComments", 1u)) {}
30 
31 void NamespaceCommentCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
32   Options.store(Opts, "ShortNamespaceLines", ShortNamespaceLines);
33   Options.store(Opts, "SpacesBeforeComments", SpacesBeforeComments);
34 }
35 
36 void NamespaceCommentCheck::registerMatchers(MatchFinder *Finder) {
37   // Only register the matchers for C++; the functionality currently does not
38   // provide any benefit to other languages, despite being benign.
39   if (getLangOpts().CPlusPlus)
40     Finder->addMatcher(namespaceDecl().bind("namespace"), this);
41 }
42 
43 static bool locationsInSameFile(const SourceManager &Sources,
44                                 SourceLocation Loc1, SourceLocation Loc2) {
45   return Loc1.isFileID() && Loc2.isFileID() &&
46          Sources.getFileID(Loc1) == Sources.getFileID(Loc2);
47 }
48 
49 static std::string getNamespaceComment(const NamespaceDecl *ND,
50                                        bool InsertLineBreak) {
51   std::string Fix = "// namespace";
52   if (!ND->isAnonymousNamespace())
53     Fix.append(" ").append(ND->getNameAsString());
54   if (InsertLineBreak)
55     Fix.append("\n");
56   return Fix;
57 }
58 
59 static std::string getNamespaceComment(const std::string &NameSpaceName,
60                                        bool InsertLineBreak) {
61   std::string Fix = "// namespace ";
62   Fix.append(NameSpaceName);
63   if (InsertLineBreak)
64     Fix.append("\n");
65   return Fix;
66 }
67 
68 void NamespaceCommentCheck::check(const MatchFinder::MatchResult &Result) {
69   const auto *ND = Result.Nodes.getNodeAs<NamespaceDecl>("namespace");
70   const SourceManager &Sources = *Result.SourceManager;
71 
72   if (!locationsInSameFile(Sources, ND->getLocStart(), ND->getRBraceLoc()))
73     return;
74 
75   // Don't require closing comments for namespaces spanning less than certain
76   // number of lines.
77   unsigned StartLine = Sources.getSpellingLineNumber(ND->getLocStart());
78   unsigned EndLine = Sources.getSpellingLineNumber(ND->getRBraceLoc());
79   if (EndLine - StartLine + 1 <= ShortNamespaceLines)
80     return;
81 
82   // Find next token after the namespace closing brace.
83   SourceLocation AfterRBrace = ND->getRBraceLoc().getLocWithOffset(1);
84   SourceLocation Loc = AfterRBrace;
85   Token Tok;
86   SourceLocation LBracketLocation = ND->getLocation();
87   SourceLocation NestedNamespaceBegin = LBracketLocation;
88 
89   // Currently for nested namepsace (n1::n2::...) the AST matcher will match foo
90   // then bar instead of a single match. So if we got a nested namespace we have
91   // to skip the next ones.
92   for (const auto &EndOfNameLocation : Ends) {
93     if (Sources.isBeforeInTranslationUnit(NestedNamespaceBegin,
94                                           EndOfNameLocation))
95       return;
96   }
97 
98   // Ignore macros
99   if (!ND->getLocation().isMacroID()) {
100     while (Lexer::getRawToken(LBracketLocation, Tok, Sources, getLangOpts()) ||
101            !Tok.is(tok::l_brace)) {
102       LBracketLocation = LBracketLocation.getLocWithOffset(1);
103     }
104   }
105 
106   auto TextRange =
107       Lexer::getAsCharRange(SourceRange(NestedNamespaceBegin, LBracketLocation),
108                             Sources, getLangOpts());
109   StringRef NestedNamespaceName =
110       Lexer::getSourceText(TextRange, Sources, getLangOpts()).rtrim();
111   bool IsNested = NestedNamespaceName.contains(':');
112 
113   if (IsNested)
114     Ends.push_back(LBracketLocation);
115   else
116     NestedNamespaceName = ND->getName();
117 
118   // Skip whitespace until we find the next token.
119   while (Lexer::getRawToken(Loc, Tok, Sources, getLangOpts()) ||
120          Tok.is(tok::semi)) {
121     Loc = Loc.getLocWithOffset(1);
122   }
123 
124   if (!locationsInSameFile(Sources, ND->getRBraceLoc(), Loc))
125     return;
126 
127   bool NextTokenIsOnSameLine = Sources.getSpellingLineNumber(Loc) == EndLine;
128   // If we insert a line comment before the token in the same line, we need
129   // to insert a line break.
130   bool NeedLineBreak = NextTokenIsOnSameLine && Tok.isNot(tok::eof);
131 
132   SourceRange OldCommentRange(AfterRBrace, AfterRBrace);
133   std::string Message = "%0 not terminated with a closing comment";
134 
135   // Try to find existing namespace closing comment on the same line.
136   if (Tok.is(tok::comment) && NextTokenIsOnSameLine) {
137     StringRef Comment(Sources.getCharacterData(Loc), Tok.getLength());
138     SmallVector<StringRef, 7> Groups;
139     if (NamespaceCommentPattern.match(Comment, &Groups)) {
140       StringRef NamespaceNameInComment = Groups.size() > 5 ? Groups[5] : "";
141       StringRef Anonymous = Groups.size() > 3 ? Groups[3] : "";
142 
143       if (IsNested && NestedNamespaceName == NamespaceNameInComment) {
144         // C++17 nested namespace.
145         return;
146       } else if ((ND->isAnonymousNamespace() &&
147                   NamespaceNameInComment.empty()) ||
148                  (ND->getNameAsString() == NamespaceNameInComment &&
149                   Anonymous.empty())) {
150         // Check if the namespace in the comment is the same.
151         // FIXME: Maybe we need a strict mode, where we always fix namespace
152         // comments with different format.
153         return;
154       }
155 
156       // Otherwise we need to fix the comment.
157       NeedLineBreak = Comment.startswith("/*");
158       OldCommentRange =
159           SourceRange(AfterRBrace, Loc.getLocWithOffset(Tok.getLength()));
160       Message =
161           (llvm::Twine(
162                "%0 ends with a comment that refers to a wrong namespace '") +
163            NamespaceNameInComment + "'")
164               .str();
165     } else if (Comment.startswith("//")) {
166       // Assume that this is an unrecognized form of a namespace closing line
167       // comment. Replace it.
168       NeedLineBreak = false;
169       OldCommentRange =
170           SourceRange(AfterRBrace, Loc.getLocWithOffset(Tok.getLength()));
171       Message = "%0 ends with an unrecognized comment";
172     }
173     // If it's a block comment, just move it to the next line, as it can be
174     // multi-line or there may be other tokens behind it.
175   }
176 
177   std::string NamespaceName =
178       ND->isAnonymousNamespace()
179           ? "anonymous namespace"
180           : ("namespace '" + NestedNamespaceName.str() + "'");
181 
182   diag(AfterRBrace, Message)
183       << NamespaceName
184       << FixItHint::CreateReplacement(
185              CharSourceRange::getCharRange(OldCommentRange),
186              std::string(SpacesBeforeComments, ' ') +
187                  (IsNested
188                       ? getNamespaceComment(NestedNamespaceName, NeedLineBreak)
189                       : getNamespaceComment(ND, NeedLineBreak)));
190   diag(ND->getLocation(), "%0 starts here", DiagnosticIDs::Note)
191       << NamespaceName;
192 }
193 
194 } // namespace readability
195 } // namespace tidy
196 } // namespace clang
197